Ultrasonic transducers comprise a plurality of transducer elements that are used to transmit and receive ultrasonic energy to generate an image of a target. Each transducer element operates as an independent point source. Generally, the greater the quantity of transducer elements, the greater the quality of the image.
There are a number of ways in which an ultrasonic transducer can be made. One manufacturing approach will be described in connection with FIG. 1. A monolithic block of piezoelectric ceramic material 10 is provided. A portion of the piezoelectric material 10 is covered by a plating material 12 wrapped therearound. Deactivation cuts 14 are made along a top surface of the plating material 12 to define a positive electrode 16 and a ground electrode 18. The deactivation cuts 14 extend into and out of the page in FIG. 1. The positive electrode 16 is formed by that portion of the plating material 12 located between the two deactivation cuts 14. The ground electrode 18 is formed by the plating material 12 outside of the two deactivation cuts 14. With the use of a wrap around plating material 12, electrical connections to the positive and ground electrodes 16, 18 can be easily made on the same surface of the piezoelectric material 10. The block of piezoelectric ceramic material 10 and the plating material 12 with the deactivation cuts 14 form a piezoelectric material/electrode assembly 24.
A flexible circuit 22 is disposed on the top of the piezoelectric material/electrode assembly 24. Electrical connections are made between individual traces of the flexible circuit 22 and the positive and ground electrodes 16, 18 in locations of each intended transducer element. For instance, wires can be soldered onto the positive and ground electrodes 16, 18 and attached to individual traces of the flexible circuit 22. A solid backer 26 is bonded to the top side of the piezoelectric material/electrode assembly 24 with the flexible circuit 22 sandwiched therebetween. One or more matching layers 28 are then attached to the bottom side of the piezoelectric material/electrode assembly 24.
A plurality of individual transducer elements are formed using a dicing saw 30 to make a plurality of parallel dices or cuts in the assembly. The dicing saw 30 is brought into contact with the assembly from the patient side of the assembly, that is, from the matching layer 28 side of the assembly. Thus, the dicing saw 30 cuts through the one or more matching layers 28, through the plating material 12, through the piezoelectric material 10, through the flexible circuit 22 and into a portion of the backer 26. A plurality of transducer elements are developed by the dicing operation. The cuts formed by the dicing saw 30 can extend in a direction that is perpendicular to the direction in which the deactivation cuts 14 extend.
The undiced portion of the backer 26 holds the diced assembly together. After the dicing operation, kerf filler can be placed in the cuts to provide structural support to the diced assembly. The kerf filler can also provide some degree of acoustic isolation between the transducer elements.
However, when dices are made in the assembly, the common ground electrode 18 is severed, and a plurality of individual ground electrodes is formed. The individual ground electrodes must be reconnected. Typically, a wire is soldered across the individual ground electrodes to reconnect the ground electrodes. This process is labor intensive and time consuming. Further, the heat from the soldering process can depolarize the piezoelectric material 10, thereby adversely affecting the performance of the transducer.
Thus, there is a need for a system and method that can minimize such concerns.